Grade 9 science exam: SNC1W practice questions, strands and how the exam counts

Each daily paper has 8 original questions worth 25 to 35 marks. The biology, chemistry and physics papers each practise one strand, and each also has topics from other courses that you can skip: the strand sections below say which. There is also a mixed Grade 9 Science (SNC1W) paper with all three sciences in one. No paper covers Earth and space science, so use the questions on this page for that strand.

How the Grade 9 science exam counts in 2026-27

In Grades 9 and 10, your final mark is now 65% classroom work, a 20% mandatory final evaluation, and 15% attendance and participation. In science, that 20% is a written exam, sat in your school board's exam period, so your board sets the date. EQAO tests Grade 9 math, not science, so your science exam is set by your school. These rules start in the 2026-27 school year and come from the Ministry of Education's Growing Success update, last changed October 14, 2026.

SNC1W has no prerequisite. It replaced the old academic (SNC1D) and applied (SNC1P) Grade 9 courses in September 2022, so older study guides with those codes cover a different set of topics. Grade 10 science (SNC2D) follows it.

What's on the SNC1W exam: the five strands

We wrote the practice questions below for this page. Try each one before you read the answer.

Grade 9 science biology: ecosystems and climate change

The daily Grade 9 Science: Biology paper fits this strand in its ecosystems and food chains, photosynthesis, respiration and human impact questions. Skip its cells, inheritance, heart and blood, digestion and disease questions: cells and organ systems come in Grade 10, and inheritance in Grade 11.

1. Energy flow. In the food chain clover, rabbit, fox, wolf, the clover stores 20 000 kJ of energy. If about 10% passes from each level to the next, how much reaches the wolf? Answer: 20 000 kJ to 2000 kJ to 200 kJ to 20 kJ. The rest is used for life processes or lost as thermal energy, which is why food chains rarely have more than four or five levels.

2. Photosynthesis and respiration. Write both word equations and explain how they keep an ecosystem in balance. Answer: photosynthesis is carbon dioxide + water → glucose + oxygen, using light energy; cellular respiration is glucose + oxygen → carbon dioxide + water, releasing energy. The products of one are the reactants of the other, so carbon and oxygen cycle between producers and consumers.

Grade 9 science chemistry: atoms and the periodic table

The daily Grade 9 Science: Chemistry paper fits this strand in its atomic structure, periodic table, states of matter and bonding questions. Skip its rates of reaction, crude oil, acids and alkalis, atmosphere and separating mixtures questions.

3. Bohr-Rutherford diagram. Aluminium has atomic number 13 and mass number 27. How many protons, neutrons and electrons does an atom have, and how are the electrons arranged? Answer: 13 protons, 27 − 13 = 14 neutrons and 13 electrons, arranged 2, 8, 3. Three shells puts aluminium in period 3, and three electrons in the outer shell puts it in group 13.

4. Compound formulas. Calcium forms Ca²⁺ ions and chlorine forms Cl⁻ ions. What is the formula of calcium chloride? Answer: two chloride ions balance one calcium ion, so the formula is CaCl₂. The Atom Builder lets you build atoms and ions shell by shell.

Grade 9 science physics: electricity

The daily Grade 9 Science: Physics paper fits this strand in its circuits, power and efficiency, and energy transfer questions. Skip its speed, forces, waves, magnets, density and radiation questions: SNC1W physics is electricity only.

5. Series and parallel. A 10 Ω and a 20 Ω resistor are connected to a 6.0 V battery. Find the current from the battery when they are in series, then in parallel. Answer: in series the resistances add to 30 Ω, so I = V ÷ R = 6.0 ÷ 30 = 0.20 A, and the voltage splits 2.0 V and 4.0 V. In parallel each resistor gets the full 6.0 V, so the currents are 0.60 A and 0.30 A, and the battery supplies 0.90 A. Build both in the Circuit Builder to check.

Read a resistance from a current and voltage graph in our Electricity course, then press Mark.

6. Efficiency. An LED bulb takes in 900 J of electrical energy in one minute and gives out 360 J as light. What is its efficiency? Answer: efficiency = useful output ÷ total input × 100% = 360 ÷ 900 × 100% = 40%. The other 540 J heats the surroundings.

Earth and space science: space exploration

7. Distances in space. Light travels about 300 000 km every second and takes about 8.3 minutes to reach Earth from the Sun. How far away is the Sun? Answer: 8.3 minutes is 498 s, and 300 000 × 498 ≈ 1.5 × 10⁸ km. That distance is one astronomical unit (AU), the unit for the solar system; beyond it, astronomers use light-years, the distance light travels in a year, about 9.5 × 10¹² km.

8. Evidence for the Big Bang. Name two pieces of evidence that the universe began in a Big Bang. Answer: light from distant galaxies is redshifted, showing they are moving away from us and the universe is expanding; and the cosmic microwave background is faint radiation left over from the early universe, found in every direction. Our Big Bang course explains both.

Use the daily papers as a practice exam

1. Pick the paper for the strand you are revising and work to the suggested time, 30 to 40 minutes.
2. Skip the questions from other courses listed in that strand's section above.
3. Write the equation, the numbers with units, and the answer with its unit.
4. Mark it, note which strand each lost mark belongs to, and revise Earth and space science with the questions on this page.

Common Grade 9 science mistakes

• Mixing up mass number and atomic number. Neutrons = mass number − atomic number.
• Thinking current is used up in a series circuit. It is the same everywhere in a series loop; the voltage is what divides.
• Adding parallel resistances. Resistors in parallel give a total smaller than the smallest one.
• Writing photosynthesis and respiration as the same reaction. They are reverses: say which one needs light.
• Calling climate change and weather the same thing. Weather is day to day; climate is the pattern over decades.

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